Rectangular Patern Array |
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Surface |
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Pixel Area |
Texture Space : (s, t) Array Coordinates |
<< ====== >> |
Object Space : (u, v) Surface Parameters |
<< ====== >> |
Image Space : (x, y) Pixel Coordinates |
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Texture - Surface Transformation |
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Viewing and projection Transformation |
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u = fu(s,t) = aus + but + cu v = fv(s,t) = avs + bvt + cv |
The basic method of texture mapping is to specify the coordinates in the texture map (s,t) that map to a particular point on the geometric surface. For polygonal models, the (s,t) coordinates are specified at the polygon vertices and are interpolated across the surface as are R,G,B,A,Z and other things to come. Normally, the texture coordinates are on the range [0..1] in u and v. However, for textures that are to repeat more than once going across the polygon, texture coordinates outside the [0..1] range need to be acceptable.